because he is so cute
anyways i saw the descriptions of him being a psychic pokemon cased in a gel thats supposed to protect him from diffrent types of weather and what not.
i how ever was thinking more like this
when this pokemon is hatched as a fetus. the fluid from his egg stays around him as a gel shield. It helps protect him from other pokemon while his mind can grow and develop. When he evolves however his gel starts becoming more of an acid that slowly starts dissolving his body. because all his muscles are undeveloped he is not able to rip off his acid gel. His protection becomes his tomb. To not die he uses his psychic powers to push back the acid fluid. Once he masters this he will evolve to reuniclus. To be able to move and fight he creates psychic arteries between the little body parts he has left and uses this as a guide line to let his body flow. A body he can move around at will which exist of a impenetrable acid gel.